Effect of extrusion ratio on discharge performance of AP65 magnesium alloy as anode for seawater activated battery

AP65 magnesium alloy is an attractive candidate for the anode of higher-power seawater activated battery because of its strong discharge activity. In practical applications, plastic forming such as hot extrusion is usually adopted to fabricate the AP65 sheets for serving as the battery anodes. Thus, the extrusion ratio obviously affects the microstructure and discharge behavior of AP65. The effect of different extrusion ratios (8.2:1, 12.3:1 and 24.5:1) on the discharge behavior and microstructure of AP65 were systematically investigated. The results indicate that the sample with the extrusion ratio of 12.3:1 has uniformly refined grains, low density of dislocations, and fractured Al8Mn5 phase, thus leading to more negative discharge potential (-1.780 V vs. SCE) and higher anodic efficiency (87.7±0.2) %) than other extruded samples. Therefore, the electrochemical performance of AP65 rises first and then declines as the extrusion ratio increases with the extrusion speed of 0.05 m/s at 450 ℃, and the discharge properties achieve the optimal value when the extrusion ratio is close to 12.3:1.